RESUMO
BACKGROUND: Deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT) is an emerging therapy to provide seizure control in patients with refractory epilepsy, although its therapeutic mechanisms remain elusive. OBJECTIVE: We tested the hypothesis that ANT-DBS might interfere with the kindling process using three experimental groups: PTZ, DBS-ON and DBS-OFF. METHODS: 79 male rats were used in two experiments and exposed to chemical kindling with pentylenetetrazole (PTZ, 30 mg/kg i.p.), delivered three times a week for a total of 18 kindling days (KD). These animals were divided into two sets of three groups: PTZ (n = 26), DBS-ON (n = 28) and DBS-OFF (n = 25). ANT-DBS (130 Hz, 90 µs, and 200 µA) was paired with PTZ injections, while DBS-OFF group, although implanted remained unstimulated. After KD 18, the first set of PTZ-treated animals and an additional group of 11 naïve rats were euthanized for brain extraction to study adenosine kinase (ADK) expression. To observe possible long-lasting effects of ANT stimulation, the second set of animals underwent a 1-week treatment and stimulation-free period after KD 18 before a final PTZ challenge. RESULTS: ANT-DBS markedly attenuated kindling progression in the DBS-ON group, which developed seizure scores of 2.4 on KD 13, whereas equivalent seizure scores were reached in the DBS-OFF and PTZ groups as early as KD5 and KD6, respectively. The incidence of animals with generalized seizures following 3 consecutive PTZ injections was 94%, 74% and 21% in PTZ, DBS-OFF and DBS-ON groups, respectively. Seizure scores triggered by a PTZ challenge one week after cessation of stimulation revealed lasting suppression of seizure scores in the DBS-ON group (2.7 ± 0.2) compared to scores of 4.5 ± 0.1 for the PTZ group and 4.3 ± 0.1 for the DBS-OFF group (P = 0.0001). While ANT-DBS protected hippocampal cells, the expression of ADK was decreased in the DBS-ON group compared to both PTZ (P < 0.01) and naïve animals (P < 0.01). CONCLUSIONS: Our study demonstrates that ANT-DBS interferes with the kindling process and reduced seizure activity was maintained after a stimulation free period of one week. Our findings suggest that ANT-DBS might have additional therapeutic benefits to attenuate seizure progression in epilepsy.
Assuntos
Núcleos Anteriores do Tálamo , Estimulação Encefálica Profunda , Excitação Neurológica , Adenosina Quinase/metabolismo , Adenosina Quinase/farmacologia , Animais , Excitação Neurológica/fisiologia , Masculino , Pentilenotetrazol , Ratos , Convulsões/induzido quimicamente , Convulsões/metabolismo , Convulsões/terapiaRESUMO
The Wistar audiogenic rat (WAR) strain is used as an animal model of epilepsy, which when submitted to acute acoustic stimulus presents tonic-clonic seizures, mainly dependent on brainstem (mesencephalic) structures. However, when WARs are exposed to chronic acoustic stimuli (audiogenic kindling-AK), they usually present tonic-clonic seizures, followed by limbic seizures, after recruitment of forebrain structures such as the cortex, hippocampus and amygdala. Although some studies have reported that hypothalamic-hypophysis function is also altered in WAR through modulating vasopressin (AVP) and oxytocin (OXT) secretion, the role of these neuropeptides in epilepsy still is controversial. We analyzed the impact of AK and consequent activation of mesencephalic neurocircuits and the recruitment of forebrain limbic (LiR) sites on the hypothalamic-neurohypophysial system and expression of Avpr1a and Oxtr in these structures. At the end of the AK protocol, nine out of 18 WARs presented LiR. Increases in both plasma vasopressin and oxytocin levels were observed in WAR when compared to Wistar rats. These results were correlated with an increase in the expressions of heteronuclear (hn) and messenger (m) RNA for Oxt in the paraventricular nucleus (PVN) in WARs submitted to AK that presented LiR. In the paraventricular nucleus, the hnAvp and mAvp expressions increased in WARs with and without LiR, respectively. There were no significant differences in Avp and Oxt expression in supraoptic nuclei (SON). Also, there was a reduction in the Avpr1a expression in the central nucleus of the amygdala and frontal lobe in the WAR strain. In the inferior colliculus, Avpr1a expression was lower in WARs after AK, especially those without LiR. Our results indicate that both AK and LiR in WARs lead to changes in the hypothalamic-neurohypophysial system and its receptors, providing a new molecular basis to better understaind epilepsy.
Assuntos
Epilepsia Reflexa , Hipotálamo/metabolismo , Excitação Neurológica/fisiologia , Sistemas Neurossecretores/metabolismo , Neuro-Hipófise/metabolismo , Estimulação Acústica , Animais , Modelos Animais de Doenças , Epilepsia Reflexa/genética , Epilepsia Reflexa/metabolismo , Epilepsia Reflexa/patologia , Epilepsia Reflexa/fisiopatologia , Regulação da Expressão Gênica , Hipocampo/metabolismo , Hipocampo/patologia , Hipocampo/fisiopatologia , Hipotálamo/patologia , Hipotálamo/fisiopatologia , Excitação Neurológica/patologia , Masculino , Sistemas Neurossecretores/patologia , Sistemas Neurossecretores/fisiopatologia , Ocitocina/sangue , Ocitocina/genética , Ocitocina/metabolismo , Neuro-Hipófise/patologia , Neuro-Hipófise/fisiopatologia , Ratos , Ratos Wistar , Convulsões/genética , Convulsões/metabolismo , Convulsões/fisiopatologia , Convulsões/psicologia , Vasopressinas/sangue , Vasopressinas/genética , Vasopressinas/metabolismoRESUMO
BACKGROUND: Variation in the temporal patterns of electrical pulses in stimulation trains has opened a new field of opportunity for the treatment of neurological disorders, such as pharmacoresistant temporal lobe epilepsy. Whether this novel type of stimulation affects epileptogenesis remains to be investigated. OBJECTIVE: The purpose of this study was to analyze the effects of temporally irregular deep brain stimulation on kindling-induced epileptogenesis in rats. METHODS: Temporally irregular deep brain stimulation was delivered at different times with respect to the kindling stimulation. Behavioral and electrographic changes on kindling acquisition were compared with a control group and a temporally regular deep brain stimulation-treated group. The propagation of epileptiform activity was analyzed with wavelet cross-correlation analysis, and interictal epileptiform discharge ratios were obtained. RESULTS: Temporally irregular deep brain stimulation delivered in the epileptogenic focus during the interictal period shortened the daily afterdischarge duration, slowed the progression of seizure stages, diminished the generalized seizure duration and interfered with the propagation of epileptiform activity from the seizure onset zone to the ipsi- and contralateral motor cortex. We also found a negative correlation between seizure severity and interictal epileptiform discharges in rats stimulated with temporally irregular deep brain stimulation. CONCLUSION: These results provide evidence that temporally irregular deep brain stimulation interferes with the establishment of epilepsy by delaying epileptogenesis by almost twice as long in kindling animals. Thus, temporally irregular deep brain stimulation could be a preventive approach against epilepsy.
Assuntos
Estimulação Encefálica Profunda/métodos , Modelos Animais de Doenças , Epilepsia/terapia , Excitação Neurológica/fisiologia , Animais , Estimulação Elétrica/métodos , Epilepsia/fisiopatologia , Masculino , Ratos , Ratos Wistar , Convulsões/fisiopatologia , Convulsões/terapia , Fatores de TempoRESUMO
Temporal lobe epilepsy is often accompanied by behavioral, electroencephalographic and autonomic abnormalities. Amygdala kindling has been used as an experimental model to study epileptogenesis. Although amygdala kindling has been extensively investigated in the context of its clinical relevance to the epilepsies, potential associated respiratory alterations are not well known. Here, our main objective was to better investigate the mechanisms involved in respiratory physiology impairment in the amygdala rapid kindling (ARK) model of epileptogenesis. Male Wistar rats with electrodes implanted into the amygdaloid complex were used. After recovery from surgery, the rats were subjected to electrical stimulation of basolateral amygdala for 2 consecutive days (10â¯stimuli/day). The ventilatory parameters were evaluated by whole body plethysmography. Thereafter, animals were also exposed to hypercapnia (7% CO2) for 3â¯h to evaluate fos protein expression in several nuclei involved in respiratory control. We observed a significant reduction in ventilation during the ictal phase elicited by ARK. We also found that 10â¯days after ARK, baseline ventilation as well as the hypercapnia ventilatory response (7% CO2) were reduced compared to control rats. The number of fos-immunoreactive neurons in the retrotrapezoid nucleus, raphe magnus and nucleus of the solitary tract were also reduced after ARK. Our results showed that ARK was able to impair breathing function, demonstrating a strong coupling between amygdala and the respiratory neurons in the brainstem, with potential impact in respiratory failures, frequently fatal, during or after epileptic seizures in chronic animal models and in patients.
Assuntos
Tonsila do Cerebelo/fisiologia , Excitação Neurológica/fisiologia , Animais , Encéfalo/fisiopatologia , Córtex Cerebral/fisiopatologia , Estimulação Elétrica/métodos , Eletroencefalografia/métodos , Epilepsia/fisiopatologia , Epilepsia do Lobo Temporal/fisiopatologia , Masculino , Neurônios/metabolismo , Ratos , Ratos Wistar , Respiração , Convulsões/fisiopatologiaRESUMO
The Wistar Audiogenic Rat (WAR) is a model whose rats are predisposed to develop seizures following acoustic stimulation. We aimed to establish the transcriptional profile of the WAR model, searching for genes that help in understanding the molecular mechanisms involved in the predisposition and seizures expression of this strain. RNA-Seq of the corpora quadrigemina of WAR and Wistar rats subjected to acoustic stimulation revealed 64 genes differentially regulated in WAR. We validated twelve of these genes by qPCR in stimulated and naive (non-stimulated) WAR and Wistar rats. Among these, Acsm3 was upregulated in WAR in comparison with both control groups. In contrast, Gpr126 and Rtel1 were downregulated in naive and stimulated WAR rats in comparison with the Wistar controls. Qdpr was upregulated only in stimulated WAR rats that exhibited audiogenic seizures. Our data show that there are genes with differential intrinsic regulation in the WAR model and that seizures can alter gene regulation. We identified new genes that might be involved in the epileptic phenotype and comorbidities of the WAR model.
Assuntos
Epilepsia Reflexa/genética , Epilepsia Reflexa/patologia , Epilepsia Reflexa/fisiopatologia , Receptores Acoplados a Proteínas G/metabolismo , Teto do Mesencéfalo/fisiopatologia , Transcriptoma/fisiologia , Estimulação Acústica/efeitos adversos , Animais , Modelos Animais de Doenças , Perfilação da Expressão Gênica , Excitação Neurológica/fisiologia , Masculino , Análise de Componente Principal , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Receptores Acoplados a Proteínas G/genética , Espectrofotometria , Teto do Mesencéfalo/metabolismoRESUMO
There are reports of patients whose epileptic seizures are prevented by means of olfactory stimulation. Similar findings were described in animal models of epilepsy, such as the electrical kindling of amygdala, where olfactory stimulation with toluene (TOL) suppressed seizures in most rats, even when the stimuli were 20% above the threshold to evoke seizures in already kindled animals. The Wistar Audiogenic Rat (WAR) strain is a model of tonic-clonic seizures induced by acute acoustic stimulation, although it also expresses limbic seizures when repeated acoustic stimulation occurs - a process known as audiogenic kindling (AK). The aim of this study was to evaluate whether or not the olfactory stimulation with TOL would interfere on the behavioral expression of brainstem (acute) and limbic (chronic) seizures in the WAR strain. For this, animals were exposed to TOL or saline (SAL) and subsequently exposed to acoustic stimulation in two conditions that generated: I) acute audiogenic seizures (only one acoustic stimulus, without previous seizure experience before of the odor test) and II) after AK (20 acoustic stimuli [2 daily] before of the protocol test). We observed a decrease in the seizure severity index of animals exposed only to TOL in both conditions, with TOL presented 20s before the acoustic stimulation in both protocols. These findings were confirmed by behavioral sequential analysis (neuroethology), which clearly indicated an exacerbation of clusters of specific behaviors such as exploration and grooming (self-cleaning), as well as significant decrease in the expression of brainstem and limbic seizures in response to TOL. Thus, these data demonstrate that TOL, a strong olfactory stimulus, has anticonvulsant properties, detected by the decrease of acute and AK seizures in WARs.
Assuntos
Estimulação Acústica , Excitação Neurológica/fisiologia , Sistema Límbico/fisiologia , Convulsões , Olfato/efeitos dos fármacos , Tolueno/farmacologia , Tonsila do Cerebelo , Animais , Tronco Encefálico , Modelos Animais de Doenças , Epilepsia Reflexa , Masculino , Ratos , Ratos WistarRESUMO
The Wistar Audiogenic Rat (WAR) is a well-characterized seizure-prone, inbred rodent strain that, when acutely stimulated with high-intensity sounds, develops brainstem-dependent tonic-clonic seizures that can evolve to limbic-like, myoclonic (forebrain) seizures when the acoustic stimuli are presented chronically (audiogenic kindling). In order to investigate possible mechanisms underlying WAR susceptibility to seizures, we evaluated Na,K-ATPase activity, Ca-ATPase activity, Mg-ATPase activity, lipid membrane composition and oxidative stress markers in whole forebrain and whole brainstem samples of naïve WAR, as compared to samples from control Wistar rats. We also evaluated the expression levels of α1 and α3 isoforms of Na,K-ATPase in forebrain samples. We observed increased Na,K-ATPase activity in forebrain samples and increased oxidative stress markers (lipid peroxidation, glutathione peroxidase and superoxide dismutase) in brainstem samples of WAR. The Ca-ATPase activity, Mg-ATPase activity, lipid membrane composition and expression levels of α1 and α3 isoforms of Na,K-ATPase were unaltered. In view of previous data showing that the membrane potentials from naïve WAR's neurons are less negative than that from neurons from Wistar rats, we suggest that Na,K-ATPase increased activity might be involved in a compensatory mechanism necessary to maintain WAR's brains normal activity. Additionally, ongoing oxidative stress in the brainstem could bring Na,K-ATPase activity back to normal levels, which may explain why WAR's present increased susceptibility to seizures triggered by high-intensity sound stimulation.
Assuntos
Tronco Encefálico/enzimologia , Estresse Oxidativo/fisiologia , Prosencéfalo/enzimologia , Convulsões , ATPase Trocadora de Sódio-Potássio/metabolismo , Estimulação Acústica/efeitos adversos , Adenosina Trifosfatases/metabolismo , Animais , Tronco Encefálico/patologia , Modelos Animais de Doenças , Glutationa Peroxidase/metabolismo , Excitação Neurológica/fisiologia , Peroxidação de Lipídeos , Neurônios/enzimologia , Prosencéfalo/patologia , Isoformas de Proteínas/metabolismo , Ratos , Ratos Wistar , Convulsões/etiologia , Convulsões/metabolismo , Convulsões/patologiaRESUMO
INTRODUCTION. The immune system and the peripheral and central nervous system are in constant communication by means of messengers and signalling molecules released, such as cytokines, neuropeptides, neurohormones and neurotransmitters, among others. Seizures are defined as the transitory appearance of signs and symptoms that trigger an abnormally excessive neuronal activity in the brain. Following seizures the generation of a neuroinflammatory process has been observed to occur, with the consequent release of proinflammatory cytokines and inflammation-mediating molecules, which make the patient more prone to epilepsy. AIM. To offer evidence suggesting and supporting the role of cytokines in the appearance of seizures and in epilepsy, since these molecules have proven to have dual properties. DEVELOPMENT. The central nervous system, by means of the blood-brain barrier, restricts the flow of activated cells and inflammation mediators released from the peripheral system towards the brain parenchyma. Moreover, there is also another series of mechanisms that contributes to the 'selective and modified' immunity of the central nervous system. The purpose of all this series of events is to limit the responses of the immune system at central level, although it has been shown that in the central nervous system they are permanently under the control and regulation of the immune system. CONCLUSIONS. Cytokines in epilepsy play a dual role with pro- and anti-convulsive properties. Seizures do not induce the expression of cytokines only inside the brain, but also peripherally.
TITLE: Citocinas y sistema nervioso: relacion con crisis convulsivas y epilepsia.Introduccion. El sistema inmune y el sistema nervioso periferico y central se encuentran en constante comunicacion a traves de mensajeros y moleculas de señalizacion liberadas, como las citocinas, los neuropeptidos, las neurohormonas y los neurotransmisores, entre otros. Las convulsiones se definen como la aparicion transitoria de signos y sintomas que inducen una actividad neuronal excesiva anormal en el cerebro; despues de una crisis convulsiva, se ha observado la generacion de un proceso neuroinflamatorio, con la consecuente liberacion de citocinas proinflamatorias y de moleculas mediadoras de inflamacion, que predisponen a la epilepsia. Objetivo. Mostrar la evidencia que sugiere y apoya el papel de las citocinas en la aparicion de crisis convulsivas y en la epilepsia, ya que estas moleculas han demostrado propiedades duales. Desarrollo. El sistema nervioso central, a traves de la barrera hematoencefalica, restringe el flujo de celulas activadas y de mediadores de inflamacion liberados desde el sistema periferico hacia el parenquima cerebral; ademas, existe otra serie de mecanismos que contribuyen a la inmunidad 'selectiva y modificada' del sistema nervioso central. Toda esta serie de eventos tiene la finalidad de limitar respuestas del sistema inmune a nivel central, aunque se ha demostrado que en el sistema nervioso central se encuentran de manera permanente bajo el control y la regulacion del sistema inmune. Conclusiones. Las citocinas en la epilepsia muestran un papel dual con propiedades pro y anticonvulsionantes. Las convulsiones no solamente inducen la expresion de citocinas dentro del cerebro, sino tambien perifericamente.
Assuntos
Sistema Nervoso Central/fisiopatologia , Citocinas/fisiologia , Epilepsia/fisiopatologia , Sistema Imunitário/fisiopatologia , Inflamação/fisiopatologia , Neuroimunomodulação/fisiologia , Sistema Nervoso Periférico/fisiopatologia , Convulsões/fisiopatologia , Animais , Barreira Hematoencefálica , Convulsivantes/toxicidade , Humanos , Sistema Hipotálamo-Hipofisário/fisiopatologia , Infecções/complicações , Infecções/fisiopatologia , Mediadores da Inflamação/metabolismo , Excitação Neurológica/efeitos dos fármacos , Excitação Neurológica/fisiologia , Camundongos , Neuropeptídeos/fisiologia , Sistemas Neurossecretores/fisiopatologia , Neurotransmissores/fisiologia , Convulsões Febris/fisiopatologia , Fator de Necrose Tumoral alfa/fisiologiaRESUMO
The relationship between sleep and epilepsy has been known since ancient times, and the modulating effects of both on each other have been widely described in clinical studies. However, the mechanisms of this correlation remain unclear. Translational research is essential for filling the gaps in our knowledge, and for developing better therapeutic approaches to improve the quality of life of epileptic patients. Excellent animal models of epilepsy are available for the investigation of various aspects of epilepsy, such as epileptogenesis and hippocampal sclerosis. These models also show an association between sleep and epilepsy, suggesting that they are suitable for translational research on this relationship. While some knowledge has been obtained from preclinical studies, the topic remains relatively unexplored. In terms of the role of sleep in modulating seizure susceptibility in epilepsy, animal sleep research is a major tool. In this review, we focus on the intricate relationship between sleep and epilepsy in the preclinical setting, using a translational science approach.
Assuntos
Epilepsia/fisiopatologia , Sono/fisiologia , Pesquisa Translacional Biomédica , Animais , Convulsivantes/farmacologia , Modelos Animais de Doenças , Epilepsia/induzido quimicamente , Epilepsia/genética , Humanos , Excitação Neurológica/fisiologia , Sono/genéticaRESUMO
It is thought that cardiovascular changes may contribute to sudden death in patients with epilepsy. To examine cardiovascular alterations that occur during epileptogenesis, we measured the heart rate of rats submitted to the electrical amygdala kindling model. Heart rate was recorded before, during, and after the induced seizures. Resting heart rate was increased in stages 1, 3, and 5 as compared with the unstimulated control condition. In the initial one third of the seizures, we observed bradycardia, which increased in intensity with increasing stage and was blocked by injecting methyl atropine. During stage 5 seizures, a rebound tachycardia was observed that also increased in intensity with increasing number of seizures. This study demonstrated the influence of seizure frequency on cardiac autonomic modulation, providing a basis for discussion of potential mechanisms that cause patients with epilepsy to die suddenly.